Alright, so I watched that video showing someone defeating the 4th(?) boss with no speed upgrades, and he was able to stay within the laser beams no problem. Yet, even when I have all the speed grades, my character still moves too sluggishly to keep up and stay within the beams. I tried this out with both keyboard and mouse controls, but nothing seems to make a difference. I honestly believe that this is something that you need to fix for THIS game, and not just say that you'll fix it for part 2. If you even think that this is something worth fixing.
Thank you so much for letting us change the control setup if we like. I'm not sure what it is, but the left side of my keyboard (especially x) typically has problems with flash games.